U.S. patent application number 11/851959 was filed with the patent office on 2008-11-13 for penetration inhibitor, method for preventing penetration of solvent ink, solvent ink for injket printer and method for producing the solvent ink.
This patent application is currently assigned to Mimaki Engineering Co., Ltd.. Invention is credited to Tomotaka Furuhata, Isao Tabayashi, Satoshi Takezawa.
Application Number | 20080281043 11/851959 |
Document ID | / |
Family ID | 38512296 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080281043 |
Kind Code |
A1 |
Furuhata; Tomotaka ; et
al. |
November 13, 2008 |
PENETRATION INHIBITOR, METHOD FOR PREVENTING PENETRATION OF SOLVENT
INK, SOLVENT INK FOR INJKET PRINTER AND METHOD FOR PRODUCING THE
SOLVENT INK
Abstract
A penetration inhibitor includes a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000. The penetration inhibitor is to be added to a
solvent ink for an inkjet printer.
Inventors: |
Furuhata; Tomotaka;
(Tomi-shi, JP) ; Takezawa; Satoshi; (Tomi-shi,
JP) ; Tabayashi; Isao; (Tomi-shi, JP) |
Correspondence
Address: |
DITTHAVONG MORI & STEINER, P.C.
918 Prince St.
Alexandria
VA
22314
US
|
Assignee: |
Mimaki Engineering Co.,
Ltd.
Tomi-shi
JP
|
Family ID: |
38512296 |
Appl. No.: |
11/851959 |
Filed: |
September 7, 2007 |
Current U.S.
Class: |
525/54.42 |
Current CPC
Class: |
C09D 11/36 20130101 |
Class at
Publication: |
525/54.42 |
International
Class: |
C09D 11/08 20060101
C09D011/08; C08G 8/34 20060101 C08G008/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2006 |
JP |
2006-278990 |
Claims
1. A penetration inhibitor comprising: a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000, the penetration inhibitor being to be added to a
solvent ink for an inkjet printer.
2. The penetration inhibitor as claimed in claim 1, wherein said
rosin-series resin comprises a rosin-modified phenolic resin.
3. The penetration inhibitor as claimed in claim 1, wherein said
rosin-series resin having weight-average molecular weight of at
least about 25,000 and at most about 40,000.
4. The penetration inhibitor as claimed in claim 1, wherein a print
medium has a hydrophilic porous surface onto which the inkjet
printer is configured to eject the solvent ink.
5. The penetration inhibitor as claimed in claim 4, wherein said
print medium is for offset printing.
6. A method for preventing penetration of solvent ink into a print
medium, comprising: adding a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000 into the solvent ink for an inkjet printer.
7. The method as claimed in claim 6, wherein said solvent ink
includes a polymer resin component which includes only said
rosin-series resin.
8. The method as claimed in claim 6, wherein said rosin-series
resin is added to said solvent ink in an amount of at least about
5% and at most about 25% by mass with respect to a total mass
amount of said solvent ink.
9. The method as claimed in claim 6, wherein said rosin-series
resin comprises a rosin-modified phenolic resin.
10. The method as claimed in claim 6, wherein said rosin-series
resin having weight-average molecular weight of at least about
25,000 and at most about 40,000.
11. The method as claimed in claim 6, wherein said rosin-series
resin is added to said solvent ink in an amount of at least about
10% and at most about 20% by mass with respect to a total mass
amount of said solvent ink.
12. The method as claimed in claim 7, wherein the polymer resin
component has weight-average molecular weight of at least about
8,000.
13. Solvent ink for an inkjet printer comprising: a solvent; and a
penetration inhibitor comprising a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000.
14. The solvent ink as claimed in claim 13, wherein said
rosin-series resin comprises a rosin-modified phenolic resin.
15. The solvent ink as claimed in claim 13, wherein said
rosin-series resin having weight-average molecular weight of at
least about 25,000 and at most about 40,000.
16. The solvent ink as claimed in claim 13, wherein said solvent
ink includes a polymer resin component which includes only said
rosin-series resin.
17. The solvent ink as claimed in claim 13, wherein said solvent
ink includes said rosin-series resin in an amount of at least about
5% and at most about 25% by mass with respect to a total mass
amount of said solvent ink.
18. A method for producing solvent ink for an inkjet printer, the
method comprising: providing a solvent; and adding a rosin-series
resin having weight-average molecular weight of at least about
16,000 and at most about 50,000 into the solvent.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Japanese Patent Application No. 2006-278990, filed
Oct. 12, 2006, entitled "PENETRATION INHIBITOR, METHOD FOR
PREVENTING PENETRATION AND SOLVENT INK." The contents of this
application are incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a penetration inhibitor, a
method for preventing penetration of solvent ink into a print
medium, solvent ink for an inkjet printer, and a method for
producing solvent ink for an inkjet printer.
[0004] 2. Discussion of the Background
[0005] Inkjet printing using such a solvent ink is widely used in
printing for signs such as advertising displays and large-sized
posters. Generally, solvent ink includes organic solvent (for
example, a glycol ether compound or cyclohexanone) as a main
component and further includes a colorant such as dye or pigment
and a binder resin.
[0006] In the inkjet printing using the solvent ink, a printed
matter is obtained in the following manner. First, the solvent ink
is ejected from an inkjet head and is deposited on a print medium
to form an image. The solvent in the solvent ink deposited on the
print medium is absorbed in the print medium or removed from the
printed surface by heating the print medium. Consequently, dried
ink adheres tightly to the printed surface to form an ink coating,
thereby obtaining the printed matter.
[0007] As print media used for the inkjet printing using the
solvent ink, PVC sheets and tarpaulins having relatively high
solvent-absorption property have been typically used. Recently, in
addition to these print media, print media having hydrophilic
porous print surface such as ink-jet print paper and offset
printing plate member are also used for the inkjet printing using
the solvent ink.
[0008] As the solvent ink used in the inkjet printing, for example,
Japanese Unexamined Patent Application Publication No. 2001-311023
discloses a solvent ink containing resin particles, Japanese
Unexamined Patent Application Publication No. 2004-224910 discloses
a solvent ink containing hydrophobic polymer of which glass
transition temperature (Tg) is 40.degree. C. or more, Japanese
Unexamined Patent Application Publication Nos. JP-A-6-240192,
JP-A-10-140060 and JP-A-10-195356 disclose solvent inks containing
predetermined resins. The contents of these publications are
incorporated by reference in their entirety.
[0009] However, the solvent inks disclosed in these publications
have the following problems. That is, there is a problem that ink
bleed easily occurs in the obtained image when the aforementioned
conventional solvent ink is used to perform inkjet printing onto a
print medium having a hydrophilic porous print surface to be
printed on because such print medium has low solvent absorbency and
the ink thus penetrates into the print medium.
[0010] When inkjet printing is performed to an offset printing
plate member by using the aforementioned conventional solvent ink,
the ink penetrates into the print medium so as to reduce the amount
of ink coating formed on the printed surface. Accordingly, the ink
coating on the obtained offset plate has insufficient water
resistance and insufficient water repellency. When this offset
plate with the insufficient amount of ink coating is used for the
offset printing, the adhesion of ink for offset printing relative
to the offset plate is poor, that is, there is a problem that
sufficient plate life is not obtained.
[0011] For the purpose of achieving the aforementioned object, the
present invention provides a penetration inhibitor, to be added to
an inkjet solvent ink for preventing the penetration of the solvent
ink into a print medium, comprising a rosin-series resin of which
weight-average molecular weight is from 16,000 to 50,000.
[0012] Using the penetration inhibitor of the present invention,
there is provided a solvent ink which can be efficiently prevented
from penetrating into a print medium even when the inkjet printing
is performed to the print medium having a hydrophilic porous
surface.
[0013] According to the solvent ink containing the penetration
inhibitor of the present invention, when inkjet printing is
performed to a plate member for offset printing, the penetration of
ink into the plate member is prevented so that the amount of an ink
coating formed on the print surface of the plate member is
increased. Accordingly, an offset printing plate with the ink
coating having sufficient water resistance and water repellency can
be obtained. When the offset printing plate is used for offset
printing, sufficient adhesion of ink for offset printing relative
to the offset printing plate can be obtained. Accordingly, the
offset printing plate has excellent plate life.
SUMMARY OF THE INVENTION
[0014] According to one aspect of the present invention, a
penetration inhibitor includes a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000. The penetration inhibitor is to be added to a
solvent ink for an inkjet printer.
[0015] According to another aspect of the present invention, a
method for preventing penetration of solvent ink into a print
medium includes adding a rosin-series resin having weight-average
molecular weight of at least about 16,000 and at most about 50,000
into the solvent ink for an inkjet printer.
[0016] According to further aspect of the present invention,
solvent ink for an inkjet printer includes a solvent and a
penetration inhibitor which includes a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000.
[0017] According to the other aspect of the present invention, a
method for producing solvent ink for an inkjet printer includes
providing a solvent and adding a rosin-series resin having
weight-average molecular weight of at least about 16,000 and at
most about 50,000 into the solvent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0019] FIG. 1 is a diagram showing a relationship between time and
water contact angles on the printing plate member A;
[0020] FIG. 2 is a diagram showing a relationship between time and
water contact angles on the printing plate member B;
[0021] FIG. 3 is a diagram showing a relationship between time and
water contact angles on the printing plate member C;
[0022] FIG. 4 is a diagram showing a relationship between time and
water contact angles on the printing plate member D; and
[0023] FIG. 5 is a diagram showing a relationship between time and
water contact angles on the printing plate member E.
DESCRIPTION OF THE EMBODIMENTS
[0024] The embodiments will now be described with reference to the
accompanying drawings, wherein like reference numerals designate
corresponding or identical elements throughout the various
drawings.
[0025] Though preferred embodiments of the present invention will
be described in detail, the present invention is not limited to the
following embodiments.
(Penetration Inhibitor)
[0026] A penetration inhibitor according to an embodiment of the
present invention, to be contained in an inkjet solvent ink for
preventing the penetration of the inkjet solvent ink into a print
medium, includes a rosin-series resin.
[0027] Rosin-series resins mean rosin modified resins. Examples
include rosin ester resins, rosin modified phenolic resins, rosin
modified maleic resins, and rosin modified alkyd resin. Among
these, the rosin modified phenolic resin is particularly preferable
because of excellent solubility relative to a typically used
solvent for the solvent ink and ejection stability of the solvent
ink. Using the rosin modified phenolic resin makes the ink to
highly exhibit the penetration inhibiting effect relative to the
print medium.
[0028] Though the reason why the aforementioned effects can be
obtained by the penetration inhibitor according to an embodiment of
the present invention is not so clear, the inventors of this
invention consider as follows.
[0029] That is, there is an ink absorptive layer on a print medium,
having a hydrophilic porous surface to be printed on, such as an
inkjet paper and an offset printing plate member. In the ink
absorptive layer, hydrophilic inorganic particles such as silicon
dioxide or aluminum oxide are dispersed in hydrophilic resin such
as polyvinyl alcohol.
[0030] When the affinity between the resin in the solvent ink and
the ink absorptive layer is excessively high, the resin penetrates
into the ink absorptive layer not to allow a sufficient amount of
resin to remain on the printing surface so that the amount of the
obtained ink coating is insufficient. On the other hand, when the
affinity between the resin in the solvent ink and the ink
absorptive layer is low, adhesion of ink to the print medium can
not be obtained.
[0031] However, since the penetration inhibitor according to an
embodiment of the present invention has a suitable affinity to
hydrophilic inorganic particles and hydrophilic resins, it is
believed that strong adhesion of ink to the print medium can be
obtained and the penetration into the print medium can be
prevented.
[0032] The rosin-series resin is preferably a rosin-modified
phenolic resin. Accordingly, the penetration inhibiting effect of
the penetration inhibitor according to an embodiment of the present
invention relative to the print medium is improved.
[0033] The print medium is preferably a print medium having a
hydrophilic porous surface to be printed on, particularly, a plate
member for offset printing. According to the print medium as
mentioned above, the penetration inhibiting effect is achieved at a
higher level.
[0034] The present invention also provides a penetration inhibiting
method, for preventing the penetration of an inkjet solvent ink
into a print medium, which comprises adding a rosin-series resin,
of which weight-average molecular weight is from 16,000 to 50,000,
into the inkjet solvent ink.
[0035] The penetration inhibiting method according to an embodiment
of the present invention can exhibit excellent penetration
inhibiting effect because the aforementioned penetration inhibitor,
that is, a rosin-series resin of which the weight-average molecular
weight is from 16,000 to 50,000 is used.
[0036] In the penetration inhibiting method according to an
embodiment of the present invention, it is preferable that only
said rosin-series resin is contained as a polymer resin component
into the inkjet solvent ink. Accordingly, the content of the
polymer resin component can be relatively reduced as a whole so as
to lower the viscosity of the solvent ink, thereby improving the
ejection stability of the solvent ink.
[0037] In the penetration inhibiting method according to an
embodiment of the present invention, it is preferable that the
rosin-series resin is contained in the inkjet solvent ink in an
amount of from 5 to 25% by mass relative to the total amount of the
solvent ink. In case that the content of the rosin-series resin is
less than 5% by mass relative to the total amount of the solvent
ink, the obtained penetration inhibiting effect is lower than that
in case that the content is in the aforementioned range. On the
other hand, in case that the content of the rosin-series resin is
more than 25% by mass relative to the total amount of the solvent
ink, the viscosity of the obtained solvent ink is higher than that
in case that the content is in the aforementioned range, thus
reducing the ejection stability.
[0038] An inkjet solvent ink according to an embodiment of the
present invention contains, as a polymer resin component, only a
penetration inhibitor as described above. Even when inkjet printing
is performed to an inexpensive inkjet paper using this inkjet
solvent ink, obtained image has less ink bleed because of the
penetration inhibiting effect.
[0039] The weight-average molecular weight of the rosin-series
resin is at least about 16,000 and at most about 50,000, preferably
at least about 25,000 and at most about 40,000. In case that the
weight-average molecular weight of the rosin-series resin is less
than about 16,000, the penetration inhibiting effect is
insufficient. On the other hand, in case that the weight-average
molecular weight of the rosin-series resin is more than about
50,000, the ejection stability of ink from the inkjet head is poor.
In case of especially poor ejection stability, printing error due
to nozzle clogging may be caused. It should be noted that the
weight-average molecular weight used in this specification is
weight-average molecular weight (Mw) with reference to polystyrene
standard which are measured by using a GPC (gel permeation
chromatography) analyzer (HLC-8220GPC available from Tosoh
Corporation) equipped with (two) columns of Shodex KF-800D and
KF-805L and using THF (tetraphdrofuran) as the eluting solvent.
[0040] The penetration inhibitor is preferably contained in an
amount of at least about 5% and at most about 25% by mass, more
preferably at least about 10% and at most about 20% by mass with
respect to the total amount of the solvent ink. In case that the
amount of the penetration inhibitor is less than about 5% by mass
relative to the total amount of the solvent ink, the aforementioned
penetration inhibiting effect is deteriorated as compared to the
case in the aforementioned range. In case that the amount of the
penetration inhibitor is more than about 25% by mass relative to
the total amount of the solvent ink, the viscosity of the solvent
ink is increased and the ejection stability is thus deteriorated as
compared to the case in the aforementioned range.
[0041] The penetration inhibitor is preferably used as a component
of the inkjet solvent ink, not used together with any polymer resin
component other than the aforementioned rosin-series resin.
However, if necessary, the penetration inhibitor may be used
together with a polymer resin component other than the
aforementioned rosin-series resin. The polymer resin used together
with the penetration inhibitor is preferably a nonbridging resin of
which molecular weight is 50,000 or less in the light of the
ejection stability for inkjet. Examples as the resin include
(styrene) acrylic resins, epoxy resins, polyester resins, modified
and/or non-modified olefin resins, silicone resins, urethane
resins, terpene resins, petroleum resins, polyamide resins, and
cellulose.
[0042] In case of also using such polymer resin component, the
amount of the polymer resin component is preferably contained in an
amount of from 0.01 to 15% by mass relative to the total amount of
the solvent ink.
[0043] The aforementioned penetration inhibitor can be added to an
inkjet solvent ink of an embodiment as will be described below, for
example.
(Penetration Inhibiting Method)
[0044] The penetration inhibiting method according to an embodiment
of the present invention is a penetration inhibiting method for
preventing penetration of inkjet solvent ink into a print medium,
which includes containing a rosin-series resin of which
weight-average molecular weight is at least about 16,000 and at
most about 50,000 into the ink for inkjet printing.
[0045] The print medium in the penetration inhibiting method of the
present invention is not limited particularly. In case that an
offset printing plate member is used as the print medium, notable
effects are obtained for the following reasons.
[0046] That is, an offset printing plate having a hydrophilic
surface and a hydrophobic surface on its outer surfaces is used in
offset printing. Ink is deposited only on the hydrophobic surface
and not on the hydrophilic surface. In this state, the ink
deposited only on the hydrophobic surface is transferred indirectly
to a print medium, thereby obtaining a printed matter.
[0047] In case that inkjet printing is performed to the offset
printing plate member to form an offset printing plate, an ink
coating formed by the printing corresponds to the hydrophobic
surface and the other portion corresponds to the hydrophilic
surface. If the ink penetrates into the print medium, the amount of
ink coating formed on the printed surface is reduced, with the
result that the ink coating has insufficient water resistance and
insufficient water repellency. When this offset printing plate with
the insufficient amount of ink coating is used for the offset
printing, the adhesion of ink for offset printing relative to the
offset printing plate is poor. Since the amount of the ink coating
is insufficient, the offset printing plate is undurable (has short
plate life) when being repeatedly used for printing.
[0048] By using the penetration inhibiting method according to an
embodiment of the present invention, however, the ink can be
prevented from penetrating into the printing plate member, thereby
obtaining an offset printing plate with sufficient water resistance
and water repellency of the ink coating. In case that the offset
printing plate is used for the offset printing, sufficient adhesion
of ink for offset printing relative to the offset printing plate
can be obtained. Since the ink coating has sufficient water
resistance and water repellency, the offset printing plate has
excellent plate life.
(Solvent Ink)
[0049] The inkjet solvent ink of this embodiment contains the
aforementioned penetration inhibitor and a solvent. Preferably,
contained as a polymer resin component in the solvent ink is only a
penetration inhibitor. The polymer resin component means a
component of which weight-average molecular weight measured by the
aforementioned GPC analyzer is about 8,000 or more (preferably
about 10,000 or more, more preferably about 15,000 or more).
[0050] Examples of the solvent include ketones such as acetone,
methyl ethyl ketone, cyclohexane, and 2-heptanone; alcohols such as
methanol, ethanol, isopropanol, n-hexyl alcohol, iso-heptyl
alcohol, 2-ethyl hexyl alcohol, n-octyl alcohol, 3-methyl-3-methoxy
butanol, and 3-methoxy butanol; ethers such as cellosolve, and
butyl cellosolve; hydrocarbons such as toluene, xylene, turpentine,
limonene, industrial volatile oil, tetrahydronaphthalene, and
decahydronaphthalene; glycols such as ethylene glycol, diethylene
glycol, thiodiethylene glycol, tridiethylene glycol, propylene
glycol, dipropylene glycol, and tripropylene glycol; glycol ether
acetates such as ethylene glycol monoethyl ether acetate, ethylene
glycol monobutyl ether acetate, diethylene glycol monoethyl ether
acetate, and diethylene glycol monobutyl ether acetate; glycol
ethers such as ethylene glycol monohexyl ether, ethylene
glycol-2-ethylhexyl ether, ethylene glycol phenyl ether, propylene
glycol monoethyl ether, propylene glycol propyl ether, propylene
glycol monobutyl ether, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, diethylene glycol monobutyl
ether, diethylene glycol hexyl ether, diethylene glycol-2-ethyl
hexyl ether, dipropylene glycol monomethyl ether, dipropylene
glycol monoethyl ether, dipropylene glycol monobutyl ether,
dipropylene glycol propyl ether, triethylene glycol monomethyl
ether, triethylene glycol monoethyl ether, triethylene glycol
monobutyl ether, and tripropylene glycol monomethyl ether; esters
such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate,
triethylene glycol di(2-ethylbutyrate), propylene carbonate, ethyl
lactate, butyl lactate, methyl acetoacetate, ethyl acetoacetate,
diacid ester (DBE), and 3-methyl-3-methoxy butyl acetate; and
pyrrolidones such as N-methyl-2-pyrrolidone, but not particularly
limited thereto. These solvents may be used alone or as a mixture
of any two or more thereof in consideration of the solubility of
used penetration inhibitor, ejection stability of ink, and the
drying property of the ink on a medium being printed. The content
of the solvent is preferably from 50 to 99% by mass relative to the
total amount of the solvent ink.
[0051] The solvent ink may contain colorants such as dye and
pigment, if necessary. As the colorant, various inorganic and
organic dyes and pigments which are generally used in inks for
inkjet printing may be used. Examples of dyes include C.I. Pigment
Yellow 93, 95, 109, 110, 120, 128, 138, 139, 151, 154, 155, 173,
180, 185, and 193, C.I. Pigment Orange 34, 36, 43, 61, 63, and 71,
C.I. Pigment Red 122, and 202, solid solution of C.I. Pigment Red
122 and 202, C.I. Pigment Blue 15:3 and 15:4, C.I. Pigment Violet
19, 23, and 33, C.I. Pigment Black 7, titanium oxide, alumina, zinc
oxide, hollow resin fine particles, mica, isinglass, and aluminum
fine particles. The particle diameter of pigment is preferably 150
nm or less in the mean particle size from the viewpoint of color
density, hue, and ink stability of the ink. On the other hand,
examples of dyes include C.I. Solvent Yellow 1, 2, 3, 13, 14, 19,
21, 22, 29, 36, 37, 38, 39, 40, 42, 43, 44, 45, 47, 62, 63, 71, 76,
79, 81, 82, 83:1, 85, 86, 88, and 151; C.I. Solvent Red 8, 27, 35,
36, 37, 38, 39, 40, 49, 58, 60, 65, 69, 81, 83:1, 86, 89, 91, 92,
97, 99, 100, 109, 118, 119, 122, 127, and 218; C.I. Solvent Blue
14, 24, 25, 26, 34, 37, 38, 39, 42, 43, 44, 45, 48, 52, 53, 55, 59,
67, and 70; and C.I. Solvent Black 3, 5, 7, 8, 14, 17, 19, 20, 22,
24, 26, 27, 28, 29, 43, and 45. These colorants may be used alone
or as a mixture of two or more thereof. On the other hand, the
solvent ink may be used as a transparent ink when containing no dye
or pigment. The colorant may be added to ink in a selected amount
suitable for desired print density without impairing ejection
stability of the ink. The content of the colorant in ink is
preferably from 0.1 to 15% by mass relative to the total amount of
the solvent ink.
[0052] The solvent ink according to an embodiment of the present
invention may contain additives other than the aforementioned
components, for example, conductivity adjusters, surfactants.
ultraviolet absorbers, antifoam agents, and antioxidants.
[0053] Examples of conductivity adjusters include carbons and ionic
compounds. In case of containing such a conductivity adjuster, the
content of the adjuster is preferably from 0.01 to 5% by mass
relative to the total amount of the solvent ink.
[0054] Examples of surfactants include polyoxyethylene alkyl ether
compounds, polyoxyethylene sorbitan compounds, and perfluoroalkyl
ethylene compounds. In case of containing such a surfactant, the
content of the surfactant is preferably from 0.01 to 3% by mass
relative to the total amount of the solvent ink.
[0055] Examples of ultraviolet absorbers include benzotriazole
compounds, hindered amine compounds, and hydroxyphenyl triazine
compounds. In case of containing such an ultraviolet absorber, the
content of the ultraviolet absorber is preferably from 0.01 to 8%
by mass relative to the total amount of the solvent ink.
[0056] Examples of antifoam agents include silicone oil, fatty acid
ester compounds, and phosphate ester compounds. In case of
containing such an antifoam agent, the content of the antifoam
agent is preferably from 0.01 to 3% by mass relative to the total
amount of the solvent ink.
[0057] Examples of antioxidants include phenolic compounds, amine
compounds, and phosphate compounds. In case of containing such an
antioxidant, the content of the antioxidant is preferably from 0.01
to 3% by mass relative to the total amount of the solvent ink.
[0058] As for values for physical properties of the solvent ink
according to an embodiment of the present invention, the solvent
ink is preferably adjusted to have a viscosity of from 3 to 15 mPaS
and have a surface tension of from about 20 to 35 mN/m. Viscosities
used in this specification are values measured by using Digital
Viscomate VM-100A (available from Yamaichi Electronics Co., Ltd.)
under an environmental temperature of 25.degree. C. Surface
tensions are values measured by using a surface tensiometer
(available from Kyowa Interface Science Co., Ltd.) of Wilhelmy
plate method type under an environmental temperature of 25.degree.
C. and an environmental humidity of 50% RH.
[0059] It is preferable that the solvent ink according to an
embodiment of the present invention is filtered by a filter of
which aperture size is from about 0.1 to 10 .mu.m if necessary to
remove rough and large particles in the ink before subjected to
inkjet printing.
(Print Medium)
[0060] The print medium to be subjected to inkjet printing
according to an embodiment of the present invention is preferably a
print medium having a hydrophilic porous print surface, such as an
inkjet paper or an offset printing plate member. Among such print
media, a surface printing plate member such as an offset printing
plate member is more preferable.
[0061] There are various kinds of surface printing plate members
according to printing systems. Most of the surface printing plate
members are plate members having a photosensitive undercoating
layer on a support and a hydrophilic layer on the surface of the
photosensitive undercoating layer (see Japanese Unexamined Patent
Application Publications No. 2001-105762 and Japanese Unexamined
Patent Application Publications No. 2003-255563). As the support of
the plate member, a metal sheet such as a steel sheet plated with
aluminum or chromium may be employed. As another cheaper support, a
water resist support such as a water resistant paper, a plastic
film, or a paper laminated with plastic may be employed. The layer
thickness of the plate member is preferably from 100 to 300 .mu.m
and the thickness of the hydrophilic layer on the surface is
preferably from 5 to 30 .mu.m.
[0062] For forming a surface printing plate, a method of forming a
hydrophilic/hydrophobic plate by exposing the plate member to laser
beam according to image information to remove the hydrophilic layer
on the exposed portion has been generally employed. On the other
hand, a method of forming a hydrophilic/hydrophobic plate by
applying a hydrophobic ink to the plate member using the inkjet
printing technique can be also employed. According to this method,
no laser is required so that a surface printing plate can be
obtained by a simple and cheaper device arrangement.
[0063] In case of using the solvent ink containing the penetration
inhibitor according to an embodiment of the present invention to
form a plate using the inkjet printing technique, an ink coating
having sufficient water resistance and water repellency is formed
on the surface of the plate member. The plate with the ink coating
formed thereon can be suitably used as an offset printing
plate.
[0064] The solvent ink containing the penetration inhibitor
according to an embodiment of the present invention can form an ink
coating having excellent adhesion even in case of inkjet printing
to a non-penetrative printing plate such as a grained aluminum
plate. Accordingly, the plate with the ink coating formed thereon
can be also suitably used as an offset printing plate.
EXAMPLES
[0065] Hereinafter, examples according to an embodiment of the
present invention will be described, but the present invention is
not limited to the following examples.
Example 1
[0066] A mixture of ethylene glycol monobutyl ether acetate and
propylene glycol monoethyl ether acetate (4:1 by volume ratio) was
prepared as a solvent and C.I. Solvent Black 7 was prepared as a
dye. After 80 parts by mass of the solvent, 2 parts by mass of the
dye, and 18 parts by mass of a penetration inhibitor shown in the
following Table 1 were mixed and solved at a temperature of
45.degree. C., the mixture was filtered by a stainless steel mesh
of which aperture size is 2 .mu.m. In this manner, a solvent ink of
Example 1 was obtained.
Examples 2, 3
[0067] Solvent inks of Examples 2 and 3 were obtained in the same
manner as Example 1 except that penetration inhibitors shown in the
following Table 1 were used. In Example 3, a mixture of 10 parts by
mass of a rosin modified ester and 8 parts by mass of an acrylic
resin was used as the penetration inhibitor.
Comparative Examples 1, 2
[0068] Solvent inks of Comparative Examples 1 and 2 were obtained
in the same manner as Example 1 except that penetration inhibitors
shown in the following Table 1 were used.
TABLE-US-00001 TABLE 1 Molecular Parts by Penetration Inhibitor
weight mass Example 1 Rosin modified phenolic resin 40,000 18
(TAMANOL 414, available from Arakawa Chemical Industries, Ltd)
Example 2 Rosin modified phenolic resin 16,000 18 (TAMANOL 340,
available from Arakawa Chemical Industries, Ltd) Example 3 Rosin
modified phenolic resin 40,000 10 (TAMANOL 414, available from
Arakawa Chemical Industries, Ltd) Acrylic resin 30,000 8
(MMA/BA/2EtHA = 70/20/10) Comparative Rosin modified ester resin
2,000 18 Example 1 (PENSEL AZ, available from Arakawa Chemical
Industries, Ltd) Comparative Styrene acrylic resin 30,000 18
Example 2 (St/BA/2EtHA = 70/15/15) MMA: methyl methacrylate, BA:
butyl acrylate, 2EtHA: 2-ethylhexyl acrylate, St: styrene
(Evaluation of Solvent Ink)
[0069] According to printing tests conducted using the following
inkjet printer and print media, the solvent inks of Examples 1
through 3 and Comparative Examples 1, 2 were evaluated.
[Inkjet Printer]
[0070] An inkjet printer as a testing machine specialized from an
inkjet printer (UJF-605C available from Mimaki Engineering Co.,
Ltd.) provided with a piezohead was employed. Though the inkjet
printer UJF-605C is a UV printer, a UV irradiator thereof was
removed for specializing as a testing machine. Printing tests were
conducted after the temperature of the inkjet head was set to a
temperature of 30.degree. C. and each of the aforementioned inks
was filled. Printing was performed with 1200 dpi/16 pass.
[Print Media]
[0071] Plate members each of which has an ink absorptive layer and
a surface hydrophilic layer formed on its support were used as the
print media. The surface hydrophilic layer had a composition in
which polyvinyl alcohol is mixed with silica particles.
Evaluation of Solvent Ink of Example 1
[0072] Printing was performed to the aforementioned print medium
using the aforementioned inkjet printer and the solvent ink of
Example 1. The obtained printed matter was dried at a temperature
of 100.degree. C. for 1 minute so as to obtain a printing plate
member A. The inkjet printing was conducted with no recognizable
nozzle aberrations such as nozzle clogging and deflection.
[0073] The printing plate member A was observed under an optical
microscope (450.times. magnification), with the result that an ink
coating formed on the printing plate member was confirmed. In
addition, the water contact angle of a printed portion (printing
rate: 100%) was measured (water drop, CA-V available from Kyowa
Interface Science Co., Ltd., after 100 msec of contact). As a
result, the water contact angle of the printed portion was
92.degree.. This means that the printed portion has high water
repellency. On the other hand, the water contact angle of
non-printed portion was 20.degree.. Accordingly, the printing plate
member A has a strong contrast of hydrophobic/hydrophilic
properties between the printed portion and the non-printed
portion.
[0074] As the offset printing was conducted by a printer Shinohara
52 with Super Tekplus ink using the printing plate member A, 5000
pieces of printed matter were outputted with good dot
reproducibility.
[0075] FIG. 1 shows variation with time (through 14,000 msec) of
the water contact angles at a portion with 25% printing rate, a
portion with 50% printing rate, a portion with 75% printing rate,
and a portion with 100% printing rate of the printing plate member
A, respectively.
[0076] As apparent from FIG. 1, the higher printing rate portion
(portion with printing ink adhered thereto) exhibits the higher
water repellency, so as to achieve a strong contrast of
hydrophobic/hydrophilic properties between the higher printing rate
portion and the lower printing rate portion (portion with little or
no printing ink adhered thereto). The variation with time of the
water contact angle was slight. It was found from this phenomenon
that the water repellency of the printing plate member A can be
maintained. That is, the ink penetration to the print media can be
efficiently prevented.
Evaluation of Solvent Ink of Example 2
[0077] A printing plate member B was obtained in the same manner as
Example 1 except that the solvent ink of Example 2 was used.
[0078] The printing plate member B was observed under the optical
microscope (450.times. magnification), with the result that an ink
coating formed on the printing plate member was confirmed. In
addition, the water contact angle of a printed portion (printing
rate: 100%) was measured, with the result that the water contact
angle of the printed portion was 88.degree..
[0079] As the offset printing was conducted in the same manner as
Example 1 except that the printing plate member B was used, 5000
pieces of printed matter were outputted with good dot
reproducibility.
[0080] FIG. 2 shows variation with time (through 14,000 msec) of
the water contact angles at a portion with 25% printing rate, a
portion with 50% printing rate, a portion with 75% printing rate,
and a portion with 100% printing rate of the printing plate member
B, respectively.
[0081] As apparent from FIG. 2, the higher printing rate portion
(portion with printing ink adhered thereto) exhibits the higher
water repellency, so as to achieve a strong contrast of
hydrophobic/hydrophilic properties between the higher printing rate
portion and the lower printing rate portion (portion with little or
no printing ink adhered thereto). The variation with time of the
water contact angle was slight. It was found from this phenomenon
that the water repellency of the printing plate member B can be
maintained. That is, the ink penetration to the print media can be
efficiently prevented.
Evaluation of Solvent Ink of Example 3
[0082] A printing plate member C was obtained in the same manner as
Example 1 except that the solvent ink of Example 3 was used.
[0083] The printing plate member C was observed under the optical
microscope (450.times. magnification), with the result that an ink
coating formed on the printing plate member was confirmed. In
addition, the water contact angle of a printed portion (printing
rate: 100%) was measured, with the result that the water contact
angle of the printed portion was 85.degree..
[0084] As the offset printing was conducted in the same manner as
Example 1 except that the printing plate member C was used, initial
4000 pieces of printed matter were outputted with good dot
reproducibility. However, half-tone portions of printed matter
between 4,000th and 5,000th were slightly blurred.
[0085] FIG. 3 shows variation with time (through 14,000 msec) of
the water contact angles at a portion with 25% printing rate, a
portion with 50% printing rate, a portion with 75% printing rate,
and a portion with 100% printing rate of the printing plate member
C, respectively.
[0086] As apparent from FIG. 3, the higher printing rate portion
(portion with printing ink adhered thereto) exhibits the higher
water repellency, so as to achieve a strong contrast of
hydrophobic/hydrophilic properties between the higher printing rate
portion and the lower printing rate portion (portion with little or
no printing ink adhered thereto). The variation with time of the
water contact angle was slight. It was found from this phenomenon
that the water repellency of the printing plate member C can be
maintained. That is, the ink penetration to the print media can be
efficiently prevented.
Evaluation of Solvent Ink of Comparative Example 1
[0087] A printing plate member D was obtained in the same manner as
Example 1 except that the solvent ink of Comparative Example 1 was
used.
[0088] The printing plate member D was observed under the optical
microscope (450.times. magnification), with the result that an ink
coating formed on the printing plate member was not confirmed. In
addition, the water contact angle of a printed portion (printing
rate: 100%) was measured, with the result that the water contact
angle of the printed portion was 48.degree..
[0089] As the offset printing was conducted in the same manner as
Example 1 except that the printing plate member D was used,
half-tone portions of printed matter were blurred from the start of
the printing.
[0090] FIG. 4 shows variation with time (through 14,000 msec) of
the water contact angles at a portion with 25% printing rate, a
portion with 50% printing rate, a portion with 75% printing rate,
and a portion with 100% printing rate of the printing plate member
D, respectively.
[0091] As apparent from FIG. 4, the water contact angles of the
printing plate member D are wholly small. This means that the
printing plate member D does not have water repellency enough for
offset printing. Since the water contact angle is decreased due to
variation with time, it was found that the water repellency of the
printing plate member D can not be maintained. That is, ink was
allowed to penetrate into the print medium.
Evaluation of Solvent Ink of Comparative Example 2
[0092] A printing plate member E was obtained in the same manner as
Example 1 except that the solvent ink of Comparative Example 2 was
used.
[0093] The printing plate member E was observed under the optical
microscope (450.times. magnification), with the result that an ink
coating formed on the printing plate member was not confirmed. In
addition, the water contact angle of a printed portion (printing
rate: 100%) was measured, with the result that the water contact
angle of the printed portion was 69.degree..
[0094] As the offset printing was conducted in the same manner as
Example 1 except that the printing plate member E was used,
half-tone portions of printed matter were blurred from the start of
the printing.
[0095] FIG. 5 shows variation with time (through 14,000 msec) of
the water contact angles at a portion with 25% printing rate, a
portion with 50% printing rate, a portion with 75% printing rate,
and a portion with 100% printing rate of the printing plate member
E, respectively.
[0096] As apparent from FIG. 5, the water contact angles of the
printing plate member E are wholly small. This means that the
printing plate member E does not have water repellency enough for
offset printing. Since the water contact angle is decreased due to
variation with time, it was found that the water repellency of the
printing plate member E can not be maintained. That is, ink was
allowed to penetrate into the print medium.
[0097] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *